Regular Expressions 101

^start of line

httpthe literal text http (case insensitive)

s?optionally matches the literal s (115₁₀ / 163₈ / 73₁₆) (case insensitive)

:the literal : (58₁₀ / 72₈ / 3A₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

wwwthe literal text www (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:[a-z0-9]-?)+

+repeats the group contents below at least once:

Character Class[a-z0-9]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-?optionally matches the literal - (45₁₀ / 55₈ / 2D₁₆)

Negated Character Class[^-\.]

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[a-z]{2,15}

{2,15}matches between 2 and 15 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

Non-Capturing Group(?:\.[a-z]{2})?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[a-z]{2}

{2}matches exactly 2 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

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Search reference

Regular Expression

^https?:\/\/www\.(?:[a-z0-9]-?)+[^-\.]\.[a-z]{2,15}(?:\.[a-z]{2})?$

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